Method for electrodeposition of cans

ABSTRACT

A method of depositing a coating onto a can body by electrolysis in which the can bodies are forced down between spaced electrodes and a current is sent between the spaced electrodes and another electrode located at a distance from the spaced electrodes. Electric potential is applied across from the can body to the other electrode and depositing of a coating takes place.

United States Patent 91 Chiappe 1 Feb. 13, 1973 METHOD FORELECTRODEPOSITION OF CANS [75] Inventor: Wayne T. Chiappe, Hinsdale,lll.

[73] Assignee: Continental Can Co., Inc., New

York,N.Y.

[22] Filed: April 9, 1971 [21] Appl. No.: 132,857

Related US. Application Data [62] Division of Set; No. 829,41l, June 2,1969.

[52] U.S. Cl ..204/181 [5 1] Int. Cl ..C23b 13/00, BOlk 5/02 [5 8] Fieldof Search 204/18 1 [56] References Cited UNITED STATES PATENTS 3,476,666Bell et al. ..204/ l8! Primary Examiner-l-loward S. WilliamsAttorneyAmericus Mitchell, Joseph E. Kerwin and William A. Dittmann 7ABSTRACT A method of depositing a coating onto a can body byelectrolysis in which the can bodies are forced down between spacedelectrodes and a current is sent between the spaced electrodes andanother electrode located at a distance from the spaced electrodes.Electric potential is applied across from the can body to the otherelectrode and depositing of a coating takes place.

10 (Ilaims, 6 Drawing Figures PATENIED 3.716.468

SHEET 10F 3 I WVENTOR WAYNE T CHIAPPE 8y JMI'QM Q A TT Y SHEET 3 [IF 3PAIENIED FEB! 3 Ian INVENTDR WAYNE T. CHIAPPE METHOD FORELECTRODEPOSITION OF CANS This application is a division of pendingapplication Ser. No. 829,411 filed, June 2, 1969, now U.S. Pat. No.3,620,952 and entitled Mechanical Apparatus for Electrodeposition ofCans by Wayne T. Chiappe and assigned to the same assignee as thepresent invention.

My invention is drawn to an automatic batch electrodepositing method forcans, and specifically, a batch electrodepositing method and apparatusfor depositing a coating on the can bodies.

It is an object of my invention to provide a method for automaticallycoating can bodies in batches.

It is another object of my invention to provide a can body feed systemfor isolating batches of can bodies and feeding them into, through, andout of the coating machine.

It is a final object of my invention-to provide even and regular coatingof the can bodies.

In brief, my invention is drawn to the isolating of a can body or abatch of can bodies, and dipping a can or a batch of can bodies into anelectroplating solution where they are plated. The edge of the canflange is rubbed against an electrode to provide electrical contact. Thebatch of can bodies is now air blasted to dryness, washed with deionizedwater, and air blasted to dryness again. After repetition of the rinsingand drying, the can body is ready for further manufacturing operations.

The above and other objects will become apparent from the followingdescription and drawings in which:

FIG. 1 shows a front view apparatus of my invention;

FIG. 2 shows a partial top view of my apparatus;

FIG. 3 shows a cross-section of FIG. 1 taken along line 3-3 showing thedischarge bar in its lower position;

FIG. 4 shows a top view of a section of the mounting plate;

FIG. 5 shows a cross-section taken along the line 5- 5 ofFIG. 4; and

FIG. 6 shows a schematic system.

My machine is adapted to be positioned in a can processing line afterthe can bodies have been formed. These bodies have neither top norbottom. As shown in FIG. 1, the can body 1, after being formed, isplaced upon a conveyor belt 2. The conveyor belt may be of any suitablematerial, such as woven mesh wire or mesh chain. Conveyor belt 2 movesthe cans along to the accumulation contoured stop bar 3. Cans are thenaccumulated on the conveyor belt in regular patterns up to and past thefeed fingers 4 and stop fingers 5. The separate bars 6 and 7 holding thefeed fingers 4 and stop fingers 5 are in the raised position at thistime. However, once a sufficient quantity'of cans has passed the fingerslocation and has filled up the conveyor beyond the area of the feedfingers and the stop fingers then the feed fingers 4 and stop fingers 5are lowered into their respective positions in adjacent cans (FIG. 2).The accumulation contoured stop bar 3 now lifts and cans are movedforward onto the solution tank loading platform 8. These can bodies aremoved by the feed fingers 4 which now move forward. The conveyor belt 2also provides a moving support for the can bodies. After the feedfingers have moved under the accumulation contoured stop bar and theentire batch of cans is on solution tank platform 8, against thesolution diagram of the control tank stop bar 9, the feed fingers arelifted to an upper position 10 and return to their original raisedposition. The accumulation contoured stop bar 3 returns to its lowerpositio'n and the stop fingers 5 are raised to allow accumulation ofcans against the accumulation contoured stop bar 3. As can bodies areconducted along the processing line, this cycle is repeated time aftertime.

Considering now the operation of the coating bath, a batch of cans sitson the solution tank platform 8, and the platform is in its raisedposition. The can centering plate 11 located above the tank platform hascan centering pins 13 located upon it in a regular pattern. This patternis shown in FIG. 2. The can centering plate 11 which has been in itsupper position is now lowered together with the can pressure plate 14 toa down position and respaces the cans laterally so that they do notquite touch each other. In this way, when the can bodies l are loweredinto the electroplating solution 15, the electroplating solutiondeposits evenly on the inside and outside of the can bodies without anybare spots caused by contact between adjacent can bodies. Top plate 12(FIGS. 1, 4 and 5) is mounted above the centering plate 11 and, asdescribed later in this disclosure, controls operation of the canimmersion. The solution tank platform 8 is made of non-metallic materialand has perforations 16 at the intervals shown in FIG. 1. As thecentering takes place, the stop bar 9 and side guides 17 (FIG. 2) moveback to allow extra space for inter-can body distance.

After the cans have been centered and respaced, the upper centeringplate remains stationary, being held in place by a stop 18. The tankplate 8 and the can pressure plate 14 are now lowered into the tank withthe cans I mounted in between the plates. The can pressure plate hasholes 16 in it to match the can centering pins 13. Holes 16 perform adual function. One is to allow the centering pins 13 to protrude throughthem. The other function is to allow solution which passes through thetank platform to rise through the perforated tank platform into the cansand out through the can pressure plate. The holes 19 in the tankplatform 8 have the dual function of allowing electrodes and solution topass through. The cans and plates now descend onto the electrodeslocated in the bottom of the tank. A stationary electrode plate 20 ismounted in the tank and made of a non-conductive material, such asmicarta or formica. Mounted at each station on the plate is a singlecathode 21 with anodes 22 located around the cathode 20. There are asmany anode and cathode stations as there are cans to be electroplated.When the can body is in its lowest position, the cathode 20 lies longthe longitudinal axis of the can body and the anodes 21 touch the canwith a press fit. Voltage is applied across the cathode and anodes, andthe plating or electrical deposition action takes place as soon as thecans establish electrical contact with the anodes. The can in contactwith each anode scrapes a portion of plating material off the anode tomake electrical contact with the anode. This mechanism serves as anautomatic on/off switch so that current is discharged between thecathode 21 and anode 22 only when a can body is in position to be coatedand at all other times, the anode 22 is promptly recoated by electricaldeposition and immediately thereafter, deposition and current flowceases. The electric potential may be reversed from that indicated abovedepending on the characteristics of the coating solution. Tank platform8 is urged into its upper position by springs or counterweights 23. Aline 24 runs over one or more pulleys 25,26 and is fastened to platform8. Theplatform is vlimited in its upward movement by stops 27. It ispushed downward by the can pressure plate 14. The can bodies are betweenthese plates and the force imparted by the can pressure plate to the topof the can bodies is transmitted by the can bodies to the tank platform.

After the electrodeposition cycle is completed, the tank platform 8 andthe pressure plate 14 move the cans upward and out of the solution andinto the original upper position. The pressure plate continues itswithdrawal to its high position carrying the centering plate 11 with it,and the discharge bar 28 sweeps the cans onto a second conveyor 29 madeof a mesh or some other porous material. An air blast 30 from above isdirected against the wet coated can bodies to remove the excess cleaningsolution. The excess cleaning solution falls into a trough 31 below theconveyor and is collected for further use. As the can moves along to thenext operation, a spray of deionized water is passed Y over the canbodies from a rinse water source 32. The

can bodies are rinsed with deionized water so that when they are dried,spots will not remain on the can bodies. The can bodies are dried by anair blast 33 and then are passed further along the conveyor to the nextoperation which may be baking in an oven 34 or some other operation inthe manufacturing process.

The coating composition used in my apparatus may be a water-dispersedcoating composition, such as a partially neutralized acrylicinterpolymer and an amine aldehyde condensation product or a polyepoxideor both. Examples of such interpolymers are found listed in the patentto Donald P. I-Iart, U.S. PAT. NO. 3,403,088, and assigned to P.P.G.Industries, Inc.

It is noted that these protective coatings have high dielectricstrength, coat metallic articles completely, have efficientelectro-depositing qualities, and result in cured films which are clear,glossy and have attractive appearance and good durability.

A cross-section through the solution tank 35 is shown in FIG. 3. Thedischarge bar 28 is shown in its lowered position where it pushes cansoff of the perforated tank platform 8 onto the conveyor belt. Thestationary electrode plate 20 is shown with one of the numerouselectrode stations in some detail. Attached to the bottom of theelectrode stations at each station are conductive wires 36,37, which arethemselves coated with a plastic or other coat 39 to avoid electricalloss because of short circuiting the electric current through thesolution with consequent loss of electric current and usable solution.

Threaded bolts 40 thread into nut 55 in the top plate 12 and areimmovably fastened into pressure plate 14 (FIGS. 4 and Rotation of thesethreaded bolts or screws causes the can body pressure plate 44 to moveupward or downward because of threaded elements fastened to the topplate. The electrical reversing motor 45 causes the chain to turn thesprockets and rotate the screws.

The motor 45 is controlled by the same master circuit that controls themotors of the various bars and plates as shown in FIG. 6. In any case,this motor drives a chain 46 around the first sprocket wheel 47, aroundan idler 48, the second sprocket wheel 49, third sprocket wheel 50,second idler 51, fourth sprocket wheel 52, and back around the motordrive gear 53. The idler pulleys 48,51 may be moved in and outindividually to adjust the tension on the chain 46. Four posts 54 orguide rods are fastened to the plate 12 and to the tank to support thetop plate and provide guides for the movable plates. The electricalreversing motor 45 is used to turn the sprockets 47, 49, 50 and 52, andthe attached threaded nuts clockwise and counterclockwise to move thepressure plate up or down. The position of the motor 45, guide shafts40, idler 48, and drive sprocket 49 and nut 55 are shown best in FIG. 5.

A schematic control box 56 with appropriate motors is shown in FIG. 6..Each of the motors 45i-and 57-61 is operated by the control box to startand stop in accord with the schedule set up in the description ofoperation and the tabular statement below. In this way, the bars, platesand side guides are operated at the appropriate time.

To summarize the operation of the machine, the following operationalsequence is provided:

First, flanged can bodies are manufactured or otherwise provided inplate position on the first wide conveyor belt or other type ofconveyor. The conveyor belt is continually moving.

Second, the cans come to rest against the accumulation contoured stopbar and back up in a pattern.

Third, after the pattern is filled, stop fingers and feed pins arelowered into the cans.

Fourth, the pattern forming head stock or contoured accumulation stopbar is raised and the feed finger bar sweeps the can bodies off onto thesolution tank platform and across to the solution tank stop bar.

Fifth, the feed bar raises and returns to its can body accumulatingposition in its raised position.

Sixth, the can pressure plate and can centering plate lower to a pointshort of touching or clamping the cans.

Seventh, the can centering plate continues to lower with centering pinsentering inside the can bodies to provide can body spacing.Simultaneously, stop bars swing away and side guides are opened upsufficiently to allow a new pattern space so that liquid can swirl upbetween the cans.

Eighth, the can body pressure plate moves down and drives the can bodieson the tank platform into the lowered deposition position in the tank,the can flanges shear into the anodes located on the non-conductiveelectrode plate.

Ninth, the coating solution and electric current operate to coat thecans.

Tenth, after the cans are coated, the can pressure plate is raised andthe solution tank platform follows it up until the solution tankplatform is in its high position.

Eleventh, the tank platform being at its discharge position, thedischarge sweep bar now lowers and sweeps the coated cans onto thesecond or discharge conveyor and the sweep bar now returns to itsholding position. The total time cycle is about 38 seconds. It is, ofcourse, realized that this cycle may be varied comprising the steps of:

blowing air along the longitudinal axis of said can whereby liquid isremoved from said can body, spraying deionized water over surfaces ofsaid can body, and

blowing air along the longitudinal axis of said can whereby liquid isremoved from said can body. 6. A method of electrodepositing a coatingsolution onto a flanged can body comprising the steps of:

mounting a plurality of elongate electrodes each having a straight edgewith their long axes parallel to each other and their long axes lying atthe periphery of a circle of about the size of the diameter of the edgeof said flanged can body;

mounting further electrode means equidistance of said elongateelectrodes;

placing said elongate electrodes and said electrode means into asolution having electrodepositing material therein;

applying an electric potential across said plurality of elongateelectrodes and said electrode means located in said solution;

forcing the flanged can body between said spaced elongate electrodes,whereby said elongate electrode straight edges and flanged can bodyscrape together to form at least one electrical contact; and

removing said flanged can bodies from said coating solution.

7. A method of electrodepositing a coating solution onto a flanged canbody as set forth in claim 6 in which. the step of forcing said flangedcan comprises the steps of:

pushing said flanged can body between the straight edges of the elongateelectrodes whereby the edges of the flange of said can body touches eachsaid straight edge; and

within scraping the flange of said can body against each straight edgeof each said elongate electrode whereby an electrical contact isestablished between said can body and said elongate electrode.

8. A method of electrodepositing a coating solution onto a flanged canbody as set forth in claim 7 in which the step of raising said flangedcan body comprises the steps of:

lifting said flanged can body from between said elongate electrodeswhereby the flange and elongate electrodes are electrically disconnectedand said coating material coats the bare spot on said elongate electrodeto stop the flow of electricity between said elongate electrode and saidfurther electrode means.

9. A method of electrodepositing a coating solution onto a flanged canbody as set forth in claim 6 in which the step of lowering a flanged canbody into a solution comprises the steps of:

orienting said can body with its long axis perpendicular to the surfaceof said coating solution;

lowering said can body directly into the coating solution wherebyturbulence and bubbles are minimized.

10. A method of electrodepositing a coating solution onto a flanged canbody as set forth in claim 6 further comprising the steps of:

blowing air along the longitudinal axis of said can whereby liquid isremoved from said can body, spraying deionized water over surfaces ofsaid can body; and

blowing air along the longitudinal axis of said can whereby said wateris removed from said can body.

1. A method of electrodepositing a coating solution onto a flanged canbody comprising the steps of: lowering a flanged can body into asolution having an electrodepositing material therein; applying anelectric potential between a plurality of anodes and a cathode locatedin said material; forcing the flanged can body down between spacedvertical anodes, whereby at least one anode and flanged can form anelectrical contact; and raising said flanged can bodies from saidcoating solution.
 2. A method of electrodepositing a coating solutiononto a flanged can body as set forth in claim 1 in which the step offorcing said flanged can comprises the steps of: pushing said flangedcan body between the anodes whereby the flange of said can touches eachsaid anodE; and scraping the flange of said can body against the side ofeach said anode whereby an electrical contact is established betweensaid can body and said anode.
 3. A method of electrodepositing a coatingsolution onto a flanged can body as set forth in claim 2 win which thestep of raising said flanged can body comprises the steps of: liftingsaid flanged can body from between said anodes whereby the flange andanode are electrically disconnected and said coating material coats thebare spot on said anode to stop the flow of electricity between saidcathode and said anode; and lifting said flanged can body to a positionabove said solution.
 4. A method of electrodepositing a coating solutiononto a flanged can body as set forth in claim 1 in which the step oflowering a flanged can body into a solution comprises the steps of:orienting said can body with its long axis perpendicular to the surfaceof said coating solution, lowering said can body directly into thecoating solution whereby turbulence and bubbles are minimized.
 5. Amethod of electrodepositing a coating solution onto a flanged can bodyas set forth in claim 1 further comprising the steps of: blowing airalong the longitudinal axis of said can whereby liquid is removed fromsaid can body, spraying deionized water over surfaces of said can body,and blowing air along the longitudinal axis of said can whereby liquidis removed from said can body.
 6. A method of electrodepositing acoating solution onto a flanged can body comprising the steps of:mounting a plurality of elongate electrodes each having a straight edgewith their long axes parallel to each other and their long axes lying atthe periphery of a circle of about the size of the diameter of the edgeof said flanged can body; mounting further electrode means withinequidistance of said elongate electrodes; placing said elongateelectrodes and said electrode means into a solution havingelectrodepositing material therein; applying an electric potentialacross said plurality of elongate electrodes and said electrode meanslocated in said solution; forcing the flanged can body between saidspaced elongate electrodes, whereby said elongate electrode straightedges and flanged can body scrape together to form at least oneelectrical contact; and removing said flanged can bodies from saidcoating solution.
 7. A method of electrodepositing a coating solutiononto a flanged can body as set forth in claim 6 in which the step offorcing said flanged can comprises the steps of: pushing said flangedcan body between the straight edges of the elongate electrodes wherebythe edges of the flange of said can body touches each said straightedge; and scraping the flange of said can body against each straightedge of each said elongate electrode whereby an electrical contact isestablished between said can body and said elongate electrode.
 8. Amethod of electrodepositing a coating solution onto a flanged can bodyas set forth in claim 7 in which the step of raising said flanged canbody comprises the steps of: lifting said flanged can body from betweensaid elongate electrodes whereby the flange and elongate electrodes areelectrically disconnected and said coating material coats the bare spoton said elongate electrode to stop the flow of electricity between saidelongate electrode and said further electrode means.
 9. A method ofelectrodepositing a coating solution onto a flanged can body as setforth in claim 6 in which the step of lowering a flanged can body into asolution comprises the steps of: orienting said can body with its longaxis perpendicular to the surface of said coating solution; loweringsaid can body directly into the coating solution whereby turbulence andbubbles are minimized.